Divalent metal phosphates have been proposed as fertilizers. These compounds advantageously provide multiple nutrients and exhibit slow, controlled release properties. To date, divalent metal phosphates have been produced as solid materials, and therefore techniques for their use as plant nutrients have been limited to the application of solids in the form of, for example, pellets. For example, U.S. Pat. No. 5,374,294 teaches a controlled, slow-release potassium divalent metal phosphate composition. These compositions are prepared by co-reacting concentrated potassium hydroxide, divalent metal oxide powder, and concentrated phosphoric acid. This reaction produces a damp dry, particulate, water insoluble potassium divalent metal phosphate.